1. Field of the Invention
The present invention relates to a polycrystal diamond thin film which can absorb a predetermined wavelength of light and emit a photoelectron, and a photocathode and electron tube using the same.
2. Related Background Art
Photocathodes used for detecting a predetermined wavelength of light to be detected, and electron tubes equipped therewith have conventionally been known. A photocathode has a light-absorbing layer for absorbing a predetermined wavelength of light and emitting a photoelectron. The light to be detected is made incident on the light-absorbing layer and then is converted into a photoelectron, whereby it can be detected. While various semiconductor materials are used for the light-absorbing layer, Japanese Patent Application Laid-Open No. HEI 10-149761 discloses polycrystal diamond as a material having a high photoelectric conversion quantum efficiency with respect to ultraviolet light.